Expressions and data

An expression reads data from the current execution. Run the source first, inspect its output, then select a field through editor mapping. The path depends on the trigger and node options.

Trigger input

input refers to the workflow’s original input. Adding a node does not replace that input with the previous node’s output.

To reproduce this diagram, enable Mapped fields only in an Edit fields node, create amount with value {{ input.amount + 5 }}, then inspect its output. Adapt set1 to the technical name offered by your mapping.

With this payload in a manual trigger:

{
  "email": "[email protected]",
  "amount": 120,
  "tags": ["demo", "priority"]
}

• {{ input.email }} reads the address.
• {{ input.amount }} reads the number 120.
• {{ input.tags[0] }} reads demo.

For a webhook receiving the same JSON as its request body, these paths become input.body.email, input.body.amount and input.body.tags[0]. Headers and URL parameters are available through input.headers and input.query.

Node output

nodes contains outputs from nodes that have already run, indexed by their technical names. If an HTTP node named http1 returns:

{
  "body": { "id": "customer-42", "active": true },
  "status": 200,
  "ok": true
}

Read the identifier with {{ nodes.http1.body.id }}. If you enable Body only, the output becomes { "id": "customer-42", "active": true } directly: use {{ nodes.http1.id }} instead.

The visible service name is not enough to infer the path. Use the technical name offered by mapping. A node on the other branch of an IF may not have run and therefore supplies no output for this execution.

Text or typed value

In Edit fields, a standalone expression preserves the value’s type:

{{ input.amount }}
{{ input.tags }}
{{ input.amount >= 100 }}

For the previous payload, these expressions produce a number, a list and a boolean respectively. In contrast, Amount: {{ input.amount }} produces the text Amount: 120. Entering just 120 in a value in this form also produces text; {{ 120 }} produces a number.

This rule depends on the destination parameter. The HTTP node’s body is text sent over the network. To send an object as JSON, use {{ JSON.stringify(input) }} and the header Content-Type: application/json. See the HTTP example for configuration.

Variables created by Edit fields

A simple field named customerId can be read as {{ vars.customerId }} or {{ customerId }}. These variables are stored as text. To preserve a number, object or list downstream, prefer the node’s typed output: {{ nodes.set1.amount }} or {{ nodes.set1.tags }}.

A dotted name such as customer.email builds a nested object in the output. It does not create a global variable named customer.email.

Objects, lists and files

• JSON object: read its properties directly. If nodes.http1.body is already an object, no conversion is needed to access nodes.http1.body.id.
• String containing JSON: use Parse JSON, for example with the field input.raw. The decoded value is available in nodes.parse1.parsed if the technical name is parse1.
• List: to select items and process them one by one, follow Process a list. The guide distinguishes the list path (source), the field within each item and the current loop item.
• File: check the encoding and metadata expected by the destination. Base64 content, a URL and a file path are not interchangeable.

Missing values

A missing path can produce null in a typed value and empty text when inserted into a string. An empty output therefore does not prove the data was supplied.

For optional text, you can write:

{{ input.name ?? 'Visitor' }}

?? replaces a missing or null value but preserves 0, false and an empty string. For a required address or identifier, add a validation condition and a rejection branch instead of inventing a default value.

If the result is unexpected, check the actual input and executed branch. Evaluation errors may also leave a diagnostic in the logs.